Safety device for boat hoists



July 16, 1946. A. R. WILHELM SAFETY DEVICE FOR BOAT HOISTS Filed Ju lys, 1945 Patented July 16, 1946 UNITED STATES PATENT OFFICE 2,404,153SAFETY DEVICE FOR BOAT HOISTS Albert R. Wilhelm, Louisville, Ky.Application July 6, 1943, Serial No. 493,659

4 Claims.

This invention relates to safety devices and more particularly todevices of this character for use in association with dual operationhoists usually of the electro-mechanical type, such hoists beingoperable either electrically or manually at the option of the operatorto suit specific conditions.

It is common to install electro-mechanical hoists on ships as part ofthe boat lowering and hoisting gear. The hoist is operated electricallyby means of large powerful electric motors which lift the boat quicklyfrom the water to the deck of the ship. Because of the speed with whichthese hoists operate, the hoist is usually stopped before the boat hasreached its cradle. The boat is then lifted the short remaining distanceby hand. For manual operation, a long, heavy crank is fitted upon asquared shaft projecting from the hoist frame and the crank is rotatedby an operator using both hands, in the manner of any ordinary heavyWindlass.

Care must be exercised when the hoist is to be manually operated, toguard against accidental starting of the motors. The motors, if started,will whip the heavy crank around, frequently crushing the skull of theoperator or otherwise seriously injuring him.

The present invention contemplates the provision of a safety device tobe applied to such a hoist which will permit the operation of the hoisteither electrically or manually as desired, but when set for operationby one means will positively prevent operation by the other.

It is an object of the present invention to provide means to block thesquared shaft of the hoist to render application of the crank impossiblewhile the hoist is being electrically operated; with movement of theblocking means to free the shaft acting to disrupt the circuit to themotor to preclude elecrical operation.

Another object of the invention is to provide such a device havinglocking means to hold the device in either of its two positions toensure continuous operation by the means chosen.

A further object of the invention is to provide a safety device in theform of an. attachment which may be secured to hoists of different makesand designs without the necessity for having a number of differentlydesigned devices for diiferent hoists.

Generally it is the object of the invention to provide a simple,practical safety device which is fool-proof in operation, economical tomanufacture, and built for rugged use and long wear.

Other objects Will appear from the following detailed description takenin the light of the drawing which accompanies and forms a part of thisspecification, and through the several figures of which like referencenumerals are used t in dicate identical parts.

In the drawing:

Figure 1 is a perspective view of a portion of an electro-mechanicalhoist having attached thereto a safety device embodying the principlesof the present invention, the safety device being set for electricaloperation of the hoist, and blocking manual operation;

Figure 2 is a medial, longitudinal, horizontal section through thesafety device shown in Figure 1, the device being set for manualoperation of the hoist;

Figure 3 is a vertical, longitudinal section taken on the line 3--3 ofthe Figure 2; and,

Figure 4 is a, vertical transverse section taken on the line 4-4 ofFigure 2.

Referring to the drawing in detail, a portion of an electro-mechanicalhoist is more or less diagrammatically shown in Figure 1. As the deviceof the present invention is adaptable to any hoist having dual operatingmeans, only a portion of a hoist frame I is shown from which pro- J'ectsa squared shaft 2. The shaft 2 is provided with appropriate gears, notshown, and forms a part of the conventional hoist. The safety device isshown at 3 fixed to the frame of the hoist by means of a bracket 4.

The safety device comprises a channel member 5 which houses a switch box6 and provides a pivotal support for a guard in the form of a lock ingbar 1. Locking bar I is in the form of a flat metal strip having aU-shaped bracket 8 riveted or otherwise secured to one face a shortdistance inwardly from the end of the bar. The bracket 8 is providedwith openings 9 through which a pivot bolt l0 passes. The bolt [0 alsoextends through openings in the side flanges of the channel member 5 andpivotally secures the looking bar to the channel. The open end of thelocking bar is provided with an extension I I having an opening [2 toreceive a locking pin 13, which may be dropped through openings I4 inthe channel member and opening l2 in the projection l I to hold thelocking bar in its inactive position Within the housing, extendingsubstantially longitudinally of the housing. Another pair of openings [5in the channel member provide means for holding the locking bar in itsactive or outward position. By slipping the pin I3 through the openings[5, the inner end of the locking bar bears against the shank of the pinand is securely held.

The switch box 6 is formed within the channel member by means of endplates is and I! fixed transversely of the channel, bridging the spacebetween the channel side flanges. These end members extend from the baseof the channel down to a point short of the edges of the side flanges,leaving suflicient room between the flanges of the channel to receivethe locking bar when it is in its inactive position within the channel.Side strips ii! are fixed to the opposite channel flanges to form withthe end plates a rectangular surface upon which a cover plate l9,provided with an underlying gasket 28}, may rest. The cover plate issecured to the end pieces and the side strips by means of screws 2!.This provides a waterproof compartment to house the switch.

An angle bracket 22 is screwed to the base of the channel and forms asupport for a fiber base 23 upon which the stationary terminals 24 areplaced. Each of the terminals 24 carries a fixed carbon contact 25 whichmay be screwed or otherwise attached to the terminals. Lead wires 26forming part of the motor circuit are attached to the terminals and passout of the safety device through an opening 21 in one side flange of thechannel member which is tapped to receive a section of conduit pipe 28.

The switch box end piece H. is provided with a well 29 to slidablyreceive the switch actuating plunger 38. Plunger fill is preferablyformed with a rounded head 3| and carries a depending pin 32 projectingfrom an arcuate recess 33 formed in the base of the plunger. A coilspring 34 surrounds the pin and has one end bearing against the innerportion of the recess 33, and its other end bearing against a gasket 35seated in the bottom of the well. A fiber washer 36, which serves as astop to limit the upward movement of the plunger 30, is seated againstthe end of the pin 32, and a sleeve 31 is in end contact with the washer36. A movable switch contact 38 of sufficient size to bridge thecontacts 25 slips over the sleeve 31., and a screw 39 passes through thesleeve 31 and washer 36, and threads into the pin 32 to complete theplunger and movable contact assembly. A spring 4i] surrounds the sleeve31, between the movable contact 38 and the washer 36, to provide themovable contact with a floating mount upon the sleeve 31.

The method of mounting this device upon a hoist is relativelyimmaterial, and the bracket 4 secured to the back of the channel memberis merely one method which may be employed. It is only important thatthe safety device shall be so mounted that the locking bar 1 will liedirectly in front of the crank shaft 2 of the hoist when the locking barhas been rotated to its outward or active position. This effectivelyblocks the end of the crank shaft and makes it impossible for the hoistoperator to place the crank upon the crank shaft.

When the locking bar has been moved to its outward position, the lockingpin it is dropped through the holes M to hold the bar in position. Inreaching this position the locking bar rotates about its pivot I i3 andthe inner projecting end of the bar contacts the rounded head of theplunger at, forcing the plunger inward against the tension of the spring32. The contact 38 will be moved until it is in contact with, andbridges, the carbon points 25, any further movement of the plunger beingcompensated for by compression of the spring 40 permitting movement ofthe contact 38 on the sleeve 31. The contact 38 will be held firmlyagainst the points 25 by the spring 30 and can tilt slightly about thesleeve 31 to ensure proper engagement with both contacts 25. When thelocking bar is in this position, the switch is closed, completing acircuit to the electric motor so that the hoist can be motor operated,

When it is desired to operate the hoist manually, the pin 13 iswithdrawn and spring 34 will immediately expand, forcing the plungeroutward and rotating the locking bar about its pivot. The locking bar isthen rotated completely around until it is within the channel member andthe locking pin inserted in the openings I4 and l2 to securely lock thebar in its inactive position. The outward movement of the plunger underthe infiuence of the spring separates the switch contacts, breaking thecircuit to the hoist motor.

It can thus be seen that when the switch contacts are closed to permitelectrical operation of the hoist, the locking bar must be in itsextended position, effectively blocking the crank shaft and preventingany possibility of a crank being used. On the other hand, as soon as thelocking bar leaves its position in front of the crank shaft, the switchpoints are separated so that under no circumstances can the electricmotors be started while the hoist crank shaft is unguarded.

While I have in the above disclosed what I believe to be a preferred andpractical embodiment of the invention, it is understood that theinvention is not limited to the specific form shown, but only as definedin the appended claims.

What I claim is:

l. A safety device for electro-mechanical hoists comprising, a housing,a locking bar pivotally secured to said housing, adapted to swingoutwardly to a position blocking the operation of said hoist bymechanical means, a switch within said housing connected in the powerline for electrical operation of the hoist, means adapted to becontacted by said guard to cause the switch to close when the lockingbar is swung outward, and means to lock the locking bar in its inwardand outward positions.

2. A safety device for electro-mechanica1 hoists comprising, a channelmember, a locking bar pivotally secured to said channel member adaptedto swing outwardly to a position blocking the operation of said hoist bymechanical means, a housing within said channel member, a spring pressedplunger protruding from said housing, a movable switch contactyieldingly carried by said plunger, fixed contacts within said housingconnected in the power line for electrical operation of said hoist to bebridged by said movable contact, said plunger adapted to be actuated bysaid locking bar to cause the switch contacts to engage as the lockingbar swings outward, and means to lock the locking bar in its inward andoutward positions.

3. A safety device for hoists of that type having a connection to apower line for electrical operation and a shaft adapted to receive acrank for manual operation comprising, a guard adapted to move to aposition in front of said shaft to prevent the application of saidcrank, a switch connected in said power line, and means adapted to becontacted by said guard to close said switch When the guard is in frontof said shaft and open the switch when the guard is not in front of saidshaft.

4. A safety device for electro-mechanical hoists comprising, a guardadapted to move to a position blocking the operation of the hoist bymechanical means, a switch connected in the power line for electricaloperation of said hoist, means adapted to be contacted by said guard toclose the switch when the guard is in its blocking position and open theswitch when the guard leaves its blocking position, and means to lockthe guard in each of its positions.

ALBERT R. WILHELM.

